[IMP] mrp: Allow to group by product and change default measure in work order report

PURPOSE
=======

Improve the work orders report

SPECIFICATION
=============

- Allow to group by product
- Set `Real Duration` as default measure

addons/mrp/models/mrp_workorder.py

@@ -33,7 +33,7 @@ class MrpWorkorder(models.Model):
     product_id = fields.Many2one(
         'product.product', 'Product',
         related='production_id.product_id', readonly=True,
-        help='Technical: used in views only.')
+        help='Technical: used in views only.', store=True)
     product_uom_id = fields.Many2one(
         'product.uom', 'Unit of Measure',
         related='production_id.product_uom_id', readonly=True,

addons/mrp/views/mrp_workorder_views.xml

@@ -280,7 +280,7 @@
         <field name="arch" type="xml">
             <graph string="Operations">
                 <field name="production_id"/>
-                <field name="duration_percent" type="measure"/>
+                <field name="duration" type="measure"/>
             </graph>
         </field>
     </record>